Algae blooms can have positive and negative effects on the environment. While they can absorb carbon dioxide from the atmosphere, they can also consume a large amount of oxygen suffocating other species. However, a new report from an international team of scientists states that by dumping iron in the seas, we can encourage bloom growth, capture carbon from the atmosphere and bury it on the ocean floor for centuries.

While the proposal by a team of scientists from more than a dozen nations would theoretically slow global warming, there are many other issues raised by the dumping iron and prompting ocean fertilization in the world’s oceans — namely the threat to marine life. Another hitch: large-scale experiments with ocean fertilisation using iron are currently banned by the international London Convention because of fears about side-effects.

Iron can have quite an effect when it’s dumped in the ocean as it spurs the growth of tiny plants, many of which absorb and trap carbon on the ocean floor when they die. The multinational team tested their theory in 2004 by dumping seven tonnes of iron sulphate, a vital nutrient for marine plants, into the Southern Ocean. They estimate that at least half of the carbon in the resulting bloom of diatoms, a type of algae, sank below 1,000 metres (3,300 ft) where it was trapped forever. The study was the first convincing evidence that carbon, absorbed by algae, can sink to the ocean bed.

In their findings, which were published in the journal Nature, the team wrote: “Iron-fertilised diatom blooms may sequester carbon for timescales of centuries in ocean bottom water and for longer in the sediments.” The team has suggested regulation by the UN to ensure that all tests are done with the strictest guidelines, but their proposals have been dismissed by many who prefer the ideas of simply cutting our emissions or grander geo-engineering schemes like reflecting sunlight with giant mirrors in space.